<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    ul {

      list-style: none;
    }

    .mi {
      position: relative;
      width: 223px;
      margin: 100px auto;
    }

    .mi input {
      width: 223px;
      height: 38px;
      padding: 0 10px;
      font-size: 14px;
      line-height: 48px;
      border: 1px solid #ececec;
      border-bottom-color: #a5a5a5;
      outline: none;
    }

    .mi .search {
      border: 1px solid #ff6700;
    }

    .result-list {
      display: none;
      position: absolute;
      left: 0;
      top: 50px;
      width: 223px;
      border: 1px solid #ececec;
      border-top: 0;
      background: #fff;
    }

    .result-list a {
      display: block;
      padding: 6px 15px;
      font-size: 12px;
      color: #424242;
      text-decoration: none;

    }

    .result-list a:hover {
      background-color: #eee;
    }
  </style>

</head>

<body>
<div class="mi">
  <input type="search" placeholder="小米笔记本">
  <ul class="result-list">
    <li><a href="#">全部商品</a></li>
    <li><a href="#">小米11</a></li>
    <li><a href="#">小米10S</a></li>
    <li><a href="#">小米笔记本</a></li>
    <li><a href="#">小米手机</a></li>
    <li><a href="#">黑鲨4</a></li>
    <li><a href="#">空调</a></li>
  </ul>
</div>
<script>
const input=document.querySelector('.mi input')
console.log(input)
input.addEventListener('focus',function (){
  document.querySelector('.result-list').style.display='block'
  input.classList.add('search')
})
input.addEventListener('blur',function (){
  document.querySelector('.result-list').style.display='none'
  input.classList.remove('search')
})



</script>
</body>

</html>